The present invention relates to a copy protection apparatus for preventing digital data recorded on a recording medium from an unauthorized copy from the recording medium. The present invention also relates to an information recording medium used in this copy protection apparatus.
Conventional multimedia information (e.g., image and audio data) recording media are developed in the form of a floppy disk, compact disk, DVD (Digital Video Disk), or the like.
Since digital data is recorded directly (compressed and coded data which can be decoded are also included) on the various types of digital recording media described above, the recorded data can be easily copied to other media without any loss, thus suffering problems such as copyright infringement.
To solve these problems, a method of encryption digital data and recording the encrypted digital data on a recording medium is available. However, deficiencies in management of encryption keys used in encrypting the recorded data inevitably allow data copy.
The present invention has been made in consideration of the above situation, and has as its object to provide a copy protection apparatus for preventing digital data recorded on a recording medium from an unauthorized copy from the recording medium.
It is another object of the present invention to provide an information recording medium used in this copy protection apparatus.
In order to achieve the above objects according to the first aspect of the present invention, there is provided a copy protection apparatus comprising:
an encryption system; and
a decryption system connected to the encryption system via a CPU bus,
wherein the encryption system comprises
first encryption means for encrypting, using a shared encryption key shared by the encryption system and the decryption system, an encrypted disk key encrypted using a disk key itself,
first transmission means for transmitting, via the CPU bus, the disk key encrypted by the first encryption means,
second encryption means for encrypting, using the shared encryption key, the encrypted disk key encrypted using the master key,
second transmission means for transmitting, via the CPU bus, the disk key encrypted by the second encryption means,
third encryption means for encrypting, using the shared encryption key, multimedia data in which electronic watermark information serving as some of the master keys is embedded,
third transmission means for transmitting, via the CPU bus, the multimedia data encrypted by the third encryption means, and
fourth transmission means for transmitting the multimedia data encrypted using the disk key, and
the decryption system comprises
first decryption means for decrypting, using the shared encryption key, the disk key transmitted from the first transmission means,
second decryption means for decrypting, using the shared encryption key, the disk key transmitted from the second transmission means,
third decryption means for decrypting, using the shared encryption key, the multimedia data transmitted from the third transmission means,
extraction means for extracting the watermark information from the multimedia data decrypted by the third decryption means,
disk key acquisition means for acquiring the disk key on the basis of the disk key decrypted by the first decryption means, the disk key decrypted by the second decryption means, the watermark information extracted by the extraction means, and a part master key corresponding to some of the master keys, and
fourth decryption means for decrypting, using the disk key acquired by the disk key acquisition means, the multimedia data transmitted from the fourth transmission means.
According to the second aspect of the present invention, there is provided a copy protection apparatus according of the first aspect, wherein the disk key acquisition means comprises:
first acquisition means for acquiring a master key candidate on the basis of the part master key and the watermark information;
second acquisition means for acquiring, using the master key candidate acquired by the first acquisition means, a first disk key candidate by decrypting the disk key decrypted by the second decryption means;
third acquisition means for acquiring, using the first disk key candidate acquired by the second acquisition means, a second disk key candidate by decrypting the disk key decrypted by the first decryption means;
determination means for determining whether the first disk key candidate acquired by the second acquisition means coincides with the second disk key candidate acquired by the third acquisition means; and
decision means for deciding the first disk key candidate as the disk key when the determination means determines that the first disk key candidate coincides with the second disk key candidate.
According to the third aspect of the present invention, there is provided a copy protection apparatus comprising:
an encryption system; and
a decryption system connected to the encryption system via a CPU bus,
wherein the encryption system comprises
first encryption means for encrypting, using a shared encryption key shared by the encryption system and the decryption system, an encrypted disk key encrypted using a disk key itself,
first transmission means for transmitting, via the CPU bus, the disk key encrypted by the first encryption means,
second encryption means for encrypting, using the shared encryption key, the encrypted disk key encrypted using the master key,
second transmission means for transmitting, via the CPU bus, the disk key encrypted by the second encryption means,
third transmission means for transmitting, via the CPU bus, the multimedia data which is decrypted by the disk key and in which electronic watermark information serving as some of the master keys is embedded, and
fourth transmission means for transmitting the multimedia data encrypted using the disk key and the watermark information, and
the decryption system comprises
first decryption means for decrypting, using the shared encryption key, the disk key transmitted from the first transmission means,
second decryption means for decrypting, using the shared encryption key, the disk key transmitted from the second transmission means,
disk key acquisition means for acquiring the disk key on the basis of the disk key decrypted by the first decryption means, the disk key decrypted by the second decryption means, the watermark information extracted by the extraction means, and a part master key corresponding to some of the master keys,
third decryption means for decrypting, using the disk key acquired by the disk key acquisition means, the multimedia data transmitted from the third transmission means,
extraction means for extracting the electronic watermark information from the multimedia data decrypted by the third decryption means, and
fourth decryption means for decrypting the multimedia data from the fourth transmission means on the basis of the electronic watermark information extracted by the extraction means and the disk key acquired by the disk key acquisition means.
According to the fourth aspect of the present invention, there is provided a copy protection apparatus comprising:
an encryption system; and
a decryption system connected to the encryption system via a CPU bus,
wherein the encryption system comprises
first encryption means for encrypting, using a shared encryption key shared by the encryption system and the decryption system, an encrypted disk key encrypted using a disk key itself,
first transmission means for transmitting, via the CPU bus, the disk key encrypted by the first encryption means,
second encryption means for encrypting, using the shared encryption key, the encrypted disk key encrypted using the master key,
second transmission means for transmitting, via the CPU bus, the disk key encrypted by the second encryption means,
third transmission means for transmitting, via the CPU bus, the multimedia data which is decrypted by the disk key and in which electronic watermark information serving as some of the master keys is embedded, and
fourth transmission means for transmitting, via the CPU bus, the multimedia data which is encrypted by the disk key and on which the electronic watermark information is superposed, and
the decryption system comprises
first decryption means for decrypting, using the shared encryption key, the disk key transmitted from the first transmission means,
second decryption means for decrypting, using the shared encryption key, the disk key transmitted from the second transmission means,
disk key acquisition means for acquiring the disk key on the basis of the disk key decrypted by the first decryption means, the disk key decrypted by the second decryption means, the watermark information extracted by the extraction means, and a part master key corresponding to some of the master keys,
third decryption means for decrypting, using the disk key acquired by the disk key acquisition means, the multimedia data transmitted from the third transmission means,
extraction means for extracting the electronic watermark information from the multimedia data decrypted by the third decryption means,
fourth decryption means for decrypting, using the disk key acquired by the disk key acquisition means, the multimedia data transmitted from the fourth transmission means, and
fifth decryption means for decrypting, using the electronic watermark information extracted by the extraction means, the multimedia data decrypted by the fourth decryption means.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.